Replaced coupler and lit the pilot it came on but did not stay on. Could the coupler be bad or is there something else I can try

How long did the flame stay, did it die the moment your took your finger off the red pilot button? Tell us more about why you replaced the thermocouple.

No the pilot stayed on about 2 minuets and the burner stayed on a little longer after that went on. The heater was out and would not stay lit thought that could be the problem. vicki

The moment the pilot goes out the thermocouple starts to cool and will shut down the burner. If the pilot remained lighted and the burner went off I'd blame the thermocouple but that's not your case. Are you saying the pilot went off and then moments later the burner shut down?

I'd recommend that Vicki disconnect the thermocouple connection at the gas valve, reseat the fitting and tighten the thermocouple connection hand tight plus a half turn or so and see if that resolves the issue. Be sure to examine the tip of the thermocouple to be sure it didn't get crushed.

If that fails to fix the issue, let us know the brand name on the water heater and approximately how old the unit is, OK?

Please be sure to answer Ballenger's last question, too.

Mark